Homointerface planar Josephson junction based on inverse proximity effect

The quality of a superconductor–normal metal–superconductor Josephson junction (JJ) depends crucially on the transparency of the superconductor–normal metal (S/N) interface. We demonstrate a technique for fabricating planar JJs with perfect S/N interfaces. The technique utilizes a strong inverse proximity effect discovered in Al/V5S8 bilayers, by which the Al layer is driven into the resistive state. The highly transparent S/N homointerface and the peculiar normal metal enable the flow of Josephson supercurrent across a 2.9 μm long weak link. Moreover, our JJ exhibits a giant critical current and a large product of the critical current and the normal state resistance.